C++抽象类练习题——games

Description:

In this problem, you should complete some classes.

You can see more details in sample input / output and main.cpp

Each gameobject will have position,speed, and 10HP.

When you select a gameobject, we will hear it’s voice.You should print this voice.

When you select a worker, you will hear “Scv good to go, sir!”

When you select a zealot, you will hear “My life for Aiur!”

When you select a tower, you will hear nothing, and you can replace it by a “~”

We describe the speed as a vector (dx, dy)

For the three gameobjects, they are (1, 1) (2, 2) and (0, 0). (Tower cannot move.)

When a object moves, you should print where he moves to.

Zealot and tower can attack other objects and their damages are 1.

Worker can repair an object.

When worker build a building, you should print a triangle by ‘*’ with different height.

For example, if the worker build a building with 3 you should print

+

+++

+++++

sample input

1 1

2 2

3 3

4

sample output

test for select:

Scv good to go, sir!

My life for Aiur

~

test for move:

Worker moves to (2, 2)

Zealot moves to (4, 4)

Tower cannot move

test for attack:

Zealot’s hp is 9

Tower’s hp is 9

test for repair:

Zealot’s hp is 10

test for build:

+

+++

+++++

+++++++

题目说明：

题目描述中三角形可能看上去可能会有些问题。高度为3的三角形，第一层为2个空格和一个+，第二层为1个空格和三个+，第三层为5个+

关于move函数，对于原本在(x,y)的对象，移动到(x+dx, y+dy)

为避免奇怪错误，repair 和 attack传参数请传gameobject*

解答：

#ifndef HEADER_H
#define HEADER_H
#include<iostream>
using namespace std;
class gameobject {
protected:
double x, y;
double dx, dy;
int hp;
public:
gameobject(double x = 0, double y = 0, double dx = 0, double dy = 0)
: x(x), y(y), dx(dx), dy(dy), hp(10) {}
virtual void select() = 0;
virtual void move() = 0;
void under_attack(int x) {
hp -= x;
}
void get_repaired() {
hp = 10;
}
int get_hp() {
return hp;
}
};
class worker : public gameobject {
public:
worker(double x = 0, double y = 0) : gameobject(x, y, 1, 1) {}
virtual void select() {
cout << "Scv good to go, sir!\n";
}
virtual void move() {
x += dx;
y += dy;
cout << "Worker moves to (" << x << ", "<< y << ")\n";
}
void repair(gameobject* g) {
g->get_repaired();
}
void build(int x) {
for (int i = 1; i <= x; i++) {
for (int j = 1; j <= x-i; j++) cout << " ";
for (int j = 1; j <= 2*i-1; j++) cout << "*";
cout << endl;
}
}
};
class zealot : public gameobject {
private:
int _attack;
public:
zealot(double x = 0, double y = 0)
: gameobject(x, y, 2, 2), _attack(1) {}
virtual void select() {
cout << "My life for Aiur!\n";
}
virtual void move() {
x += dx;
y += dy;
cout << "Zealot moves to (" << x << ", "<< y << ")\n";
}
void attack(gameobject* g) {
g->under_attack(_attack);
}
};
class tower : public gameobject {
private:
int _attack;
public:
tower(double x = 0, double y = 0)
: gameobject(x, y, 0, 0), _attack(1) {}
virtual void select() {
cout << "~\n";
}
virtual void move() {
cout << "Tower cannot move.\n";
}
void attack(gameobject* g) {
g->under_attack(_attack);
}
};
#endif

测试函数：

#include"header.h"
int main() {
gameobject* g;  // gameobject是一个抽象类
worker* w;  // worker zealot tower是派生类
zealot* z;
tower* t;
double x, y;  // (x, y)表示坐标
cin >> x >> y;
w = new worker(x, y);
cin >> x >> y;
z = new zealot(x, y);
cin >> x >> y;
t = new tower(x, y);
// test for select
cout << "test for select:\n";
// 当一个对象被选中时，输出他们的语音。
g = w;
g->select();
g = z;
g->select();
g = t;
g->select();
// test for move
cout << "\ntest for move:\n";
// 当一个对象移动时，输出他们移动到的位置。
g = w;
g->move();
g = z;
g->move();
g = t;
g->move();
// test for others
cout << "\ntest for attack:\n";
z->attack(t);
t->attack(z);
cout << "Zealot's hp is " << z->get_hp() << endl;
cout << "Tower's hp is " << t->get_hp() << endl;
cout << "\ntest for repair:\n";
w->repair(z);  // worker将zealot的HP修复至10
cout << "Zealot's hp is " << z->get_hp() << endl;
int h;
cin >> h;
cout << "\ntest for build:\n";
w->build(h);
delete w;
delete z;
delete t;
return 0;
}

心得体会：

games是一道抽象类的基础题

我自己写的父类定义如下：

class gameobject {
public:
virtual void select() = 0;
virtual void move() = 0;
virtual void attack(gameobject* t) = 0;
virtual int get_hp() = 0;
int hp;
gameobject() {hp = 10;}
};

要注意的一个基本的知识点是，抽象类跟继承是紧密联系在一起的父类是抽象类，其中定义一些virtual的函数，在父类本身不能实例化需要在继承父类的子类中实例化，而且，父类中的virtul函数，在子类中，【都要实例化】，不管你需不需要。

父类中也可以定义一些非virtual的函数，这些函数可以在父类中实例化。

BTW，这是TA定义的抽象父类：

class gameobject {
protected:
double x, y;
double dx, dy;
int hp;
public:
gameobject(double x = 0, double y = 0,
double dx = 0, double dy = 0)
: x(x), y(y), dx(dx), dy(dy), hp(10) {}
virtual void select() = 0;
virtual void move() = 0;
void under_attack(int x) {
hp -= x;
}
void get_repaired() {
hp = 10;
}
int get_hp() {
return hp;
}
};

把hp等定义为protected，这样对子类来说是public的，对main来说是private的，保护了成员变量。